121217561 has 2 divisors, whose sum is σ = 121217562. Its totient is φ = 121217560.

The previous prime is 121217557. The next prime is 121217597. The reversal of 121217561 is 165712121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 115433536 + 5784025 = 10744^2 + 2405^2 .

It is a cyclic number.

It is not a de Polignac number, because 121217561 - 2² = 121217557 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 121217561.

It is not a weakly prime, because it can be changed into another prime (121217461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60608780 + 60608781.

It is an arithmetic number, because the mean of its divisors is an integer number (60608781).

Almost surely, 2^121217561 is an apocalyptic number.

It is an amenable number.

121217561 is a deficient number, since it is larger than the sum of its proper divisors (1).

121217561 is an equidigital number, since it uses as much as digits as its factorization.

121217561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 840, while the sum is 26.

The square root of 121217561 is about 11009.8846951274. The cubic root of 121217561 is about 494.9050064287.

Adding to 121217561 its reverse (165712121), we get a palindrome (286929682).

The spelling of 121217561 in words is "one hundred twenty-one million, two hundred seventeen thousand, five hundred sixty-one".